So the solar system is really quite enormous. 所以，太阳系确实是巨大的。

By the time we reach Pluto¹, we have come so far that the Sun 当我们抵达冥王星的时候，我们已经走得那么遥远，太阳

our dear, warm, skin-tanning, life-giving Sun 我们那暖暖和和、晒黑我们皮肤、赋予我们生命的亲爱的太阳

has shrunk to the size of a pinhead. It is little more than a bright star. 已经缩小到了针尖大小。它比一颗明亮的恒星大不了多少。

In such a lonely void you can begin to understand how even the most significant objects 在这样冷清清的空间里，你会开始理解，为什么即使是最重要的物体

Pluto's moon, for example—have escaped attention. 比如冥王星的卫星--也逃过了人们的注意力。

In this respect, Pluto has hardly been alone. 在这方面，绝不只是冥王星。

Until the Voyager expeditions, Neptune² was thought to have two moons; Voyager found six more. 在"旅行者"号探险之前，人们以为海王星只有两颗卫星，"旅行者"号又发现了6颗。

When I was a boy, the solar system was thought to contain thirty moons. 在我小时候，人们以为太阳系只有30颗卫星。

The total now is "at least ninety,"about a third of which have been found in just the last ten years. 现在的卫星总数至少已经达到90颗，其中起码三分之一是在刚刚过去的10年里发现的。

The point to remember, of course, is that when considering the universe at large we don't actually know what is in our own solar system. 在考虑整个宇宙的时候，你当然需要记住，我们其实还不知道我们太阳系的家底。

Now the other thing you will notice as we speed past Pluto is that we are speeding past Pluto. 现在，当我们飞越冥王星的时候，你会注意到另一件事：我们在飞越冥王星。

If you check your itinerary³, you will see that this is a trip to the edge of our solar system, 要是你查一查旅行计划，你会明白这次旅行的目的地是我们太阳系的边缘，

and I'm afraid we're not there yet. 我们恐怕还没有到达。

Pluto may be the last object marked on schoolroom charts, 冥王星也许是标在教室挂图上的最后一个物体，

but the system doesn't end there. 但太阳系并不到此为止。

In fact, it isn't even close to ending there. 实际上，离终点还远着呢。

We won't get to the solar system's edge until we have passed through the Oort cloud, 要到达太阳系的边缘，我们非得穿过奥尔特云，

a vast celestial⁴ realm of drifting comets, 那是个彗星飘游的茫茫天际。

and we won't reach the Oort cloud for another. I'm so sorry about this—ten thousand years. 而我们--我为此感到很遗憾-还要再花1万年时间才能抵达奥尔特云。

Far from marking the outer edge of the solar system, 冥王星远不是太阳系外缘的标志，

as those schoolroom maps so cavalierly imply, 就像教室里的挂图上随便暗示的那样，

Pluto is barely one-fifty-thousandth of the way. 它仅仅是在五万分之一路程的地方。